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101.
Alba Poerio Alessandra Bendini Lorenzo Cerretani Matteo Bonoli‐Carbognin Giovanni Lercker 《European Journal of Lipid Science and Technology》2008,110(4):368-372
Several studies have suggested that the phenolic fraction plays an important role during storage and therefore in the shelf life of virgin olive oil. This investigation examines the effect of freezing olives (–18 °C) before processing into oil on the transfer of the phenolic compounds into the subsequent oil, and the consequential changes in oxidative stability. Oil samples obtained from frozen olives (24 h at –18 °C), crushed with and without preliminary thawing, were compared to a control sample; both oils were obtained using a two‐phase low‐scale mill. The oxidative stability in different samples was assessed in terms of primary and secondary oxidation products as measured by peroxide values and oxidative stability index times, respectively. The quality of the oil samples was also checked through the percentage of free acidity and the phenolic content. Phenols were determined by both spectrophotometric assays (total phenols and o‐diphenols) and HPLC‐DAD/MSD. The antiradical capacity of the phenolic fraction was determined by DPPH and ABTS spectrophotometric tests. These analyses showed that thawing of olives before oil extraction led to a significant loss of oxidative stability and phenols; in contrast, samples obtained from frozen olives that were not thawed before crushing showed qualitative characteristics similar to control samples. 相似文献
102.
Silipo A Sturiale L Garozzo D Erbs G Jensen TT Lanzetta R Dow JM Parrilli M Newman MA Molinaro A 《Chembiochem : a European journal of chemical biology》2008,9(6):896-904
Lipopolysaccharides (LPSs) are major components of the cell surface of Gram-negative bacteria. LPSs comprise a hydrophilic heteropolysaccharide (formed by the core oligosaccharide and the O-specific polysaccharide) that is covalently linked to the glycolipid moiety lipid A, which anchors these macromolecules to the external membrane. LPSs are one of a group of molecules called pathogen-associated molecular patterns (PAMPs) that are indispensable for bacterial growth and viability, and act to trigger innate defense responses in eukaryotes. We have previously shown that LPS from the plant pathogen Xanthomonas campestris pv. campestris (Xcc) can elicit defense responses in the model plant Arabidopsis thaliana. Here we have extended these studies by analysis of the structure and biological activity of LPS from a nonpathogenic Xcc mutant, strain 8530. We show that this Xcc strain is defective in core completion and introduces significant modification in the lipid A region, which involves the degree of acylation and nonstoichiometric substitution of the phosphate groups with phosphoethanolamine. Lipid A that was isolated from Xcc strain 8530 did not have the ability to induce the defense-related gene PR1 in Arabidopsis, or to prevent the hypersensitive response (HR) that is caused by avirulent bacteria as the lipid A from the wild-type could. This suggests that Xcc has the capacity to modify the structure of the lipid A to reduce its activity as a PAMP. We speculate that such effects might occur in wild-type bacteria that are exposed to stresses such as those that might be encountered during plant colonization and disease. 相似文献
103.
104.
Sílvia Cristina Sobottka Rolim de Moura Paulo Eduardo da Rocha Tavares Sílvia Pimentel Marconi Germer Alba Lucia Andrade Coelho Nisida Adriana Barreto Alves Alexandre Saikali Kanaan 《Food and Bioprocess Technology》2012,5(6):2488-2496
The objective of this study was to monitor the stability of anthocyanin and phenolic compounds contained in two formulations of blackberry jam (traditional and low-sugar) during storage. For that purpose, jams were prepared with varying amounts of hydrocolloids and investigated as to pH, total soluble solids, water activity, total acidity, total anthocyanins and total polyphenols. In order to accompany and assess the levels of phenolic compounds and colour (L*, a* and b*) changes, the samples were stored for 180 days at two different temperatures (10 and 25 °C). The Arrhenius model was used to determine the relationship between the reaction rate (k) at the different storage temperatures, yielding activation energy values of 19 and 12 kcal/mol and Q 10 values of 3.0 and 2.0 for traditional and low-sugar jams, respectively. The results show that by the end of the storage time investigated, the anthocyanin compounds had been partially degraded, with the greatest loss being observed in traditional jam stored at 25 °C. Colour stability was also lower in traditional jam as compared to the low-sugar product. 相似文献
105.
Jesús Trevio Carmen Centeno Luis T Ortiz Rafael Caballero 《Journal of the science of food and agriculture》1995,67(3):393-397
Two trials were conducted to determine the sugars, fructans and starch in oat plants (Avena sativa L) and the changes occurring in these carbohydrate fractions during field drying in the haymaking process. The composition of oat herbage in non-structural carbohydrates varied markedly between years; the contents of sugars, fractals and starch in both leaf blade and non-leaf blade materials being nether in 1990–1991 than in 1991–1992. Field drying produced a significant decrease (P < 0.05) in the amount of soluble carbohydrates. For the whole aerial plant parts, the decline in the fructans concentration ranged between 42.8 and 38.2% and that of sugars between 16.5 and 5.8%. The total losses of sugars and fractions in hay, expressed as losses of dry matter, ranged from 88 to 63 g kg?1 depending on the year. 相似文献
106.
Jesús Trevio Carmen Centeno Luis Ortiz Rafael Caballero 《Journal of the science of food and agriculture》1994,64(3):337-339
Common vetch (Vicia sativa L) was harvested and allowed to dry in the open air. The composition of fresh forage in non-structural carbohydrates varied markedly between years, the contents of sugars and starch in both leaves and stems being much higher in 1990-91 than 1991-92. Field drying produced a significant decrease in the amounts of these carbohydrates. The total losses of sugars and starch in hay, expressed as losses of dry matter, ranged from 28 to 15 g kg-1, depending on the year. 相似文献
107.
Lipid kinases and phosphatases play essential roles in signal transduction processes involved in cytoskeletal rearrangement,
membrane trafficking, and cellular differentiation. Phosphatidic acid (PtdOH) is an important mediator lipid in eukaryotic
cells, but little is known regarding its regulation in the parasite Trypanosoma cruzi, an agent of Chagas disease. In order to clarify the relationship between PtdOH metabolism and developmental stages of T. cruzi, epimastigotes in culture were subjected to hyperosmotic stress (~1,000 mOsm/L), mimicking the environment in the rectum
of vector triatomine bugs. These experimental conditions resulted in differentiation to an intermediate form between epimastigotes
and trypomastigotes. Morphological changes of epimastigotes were correlated with an increase in PtdOH mass accomplished by
increased enzyme activity of diacylglycerol kinase (DAGK, E.C. 2.7.1.107) and concomitant decreased activity of phosphatidate
phosphatases type 1 and type 2 (PAP1, PAP2, E.C. 3.1.3.4). Our results indicate progressive increases of PtdOH levels during
the differentiation process, and suggest that the regulation of PtdOH metabolism is an important mechanism in the transition
from T. cruzi epimastigote to intermediate form. 相似文献
108.
Dr. Cristina Tintori Ilaria Laurenzana Francesco La Rocca Dr. Federico Falchi Prof. Fabio Carraro Alba Ruiz Prof. José A. Esté Miroslava Kissova Dr. Emmanuele Crespan Prof. Giovanni Maga Prof. Mariangela Biava Dr. Chiara Brullo Prof. Silvia Schenone Prof. Maurizio Botta 《ChemMedChem》2013,8(8):1353-1360
Hematopoietic cell kinase (Hck) is a member of the Src family of non‐receptor protein tyrosine kinases. High levels of Hck are associated with drug resistance in chronic myeloid leukemia. Furthermore, Hck activity has been connected with HIV‐1. Herein, structure‐based drug design efforts were aimed at identifying novel Hck inhibitors. First, an in‐house library of pyrazolo[3,4‐d]pyrimidine derivatives, which were previously shown to be dual Abl and c‐Src inhibitors, was analyzed by docking studies within the ATP binding site of Hck to select the best candidates to be tested in a cell‐free assay. Next, the same computational protocol was applied to screen a database of commercially available compounds. As a result, most of the selected compounds were found active against Hck, with Ki values ranging from 0.14 to 18.4 μM , confirming the suitability of the computational approach adopted. Furthermore, selected compounds showed an interesting antiproliferative activity profile against the human leukemia cell line KU‐812, and one compound was found to block HIV‐1 replication at sub‐toxic concentrations. 相似文献
109.
M. Melgosa M. M. Prez E. Hita M. J. Moyano J. Alba F. J. Heredia 《Journal of the American Oil Chemists' Society》2000,77(10):1093-1100
Twenty experienced observers with nondefective color vision judged 27 virgin olive oil samples within an acceptable color
range, using the bromthymol blue (BTB) method, under controlled observation conditions (daylight source with a correlated
color temperature of 6500 K, and standard gray back-ground). On the average, 44.8% of the observers agreed in their selections
of the BTB standard solution matching a given oil sample, and this percentage increased to 88.2% considering ±one step in
the two dimensions (pH and concentration) of the BTB scale. On the average, the lowest color difference between oil samples
and available BTB solutions was 6.6 Commission Internationale de l'éclairage 1976-(L*a*b*) (CIELAB) units, but this color difference was approximately two times greater for the color difference between oil samples
and BTB solutions selected by our observers. The colors of the BTB standard solutions in the CIELAB space are not uniformly
distributed, and thus one step in pH or concentration is equivalent to CIELAB color differences varying in a wide range (1.7–13.5
and 1.7–26.3 CIELAB units, respectively). From these values, indicating low precision, accuracy, and uniformity, some suggestions
are made for future improvements of the current BTB method. 相似文献
110.
Poly (2-ethyl-2-oxazoline) (PEOZ) is one of the commercial members of a family of materials that have shown significant application
potential in a large number of technological contexts, most of them related with biomedical problems where water-soluble polymer
systems are highly desirable. Polymeric fibers with diameters in the 200–800 nm range of PEOZ were prepared by electrospinning
of its water solutions. Processing and solution parameters effects on the morphology and the diameter of the fibers were investigated.
SEM results showed that the polymer concentration and the applied voltage might be used as variables to control the morphology
and the diameter of the electrospun fibers. Solutions of the same polymer in other two organic solvents (N,N-dimethylformamide (DMF) and tetrahydrofurane (THF)) were also processed by the same technique but without the promising results
of the water solutions. 相似文献